Centrifugal fan and electronic device

ABSTRACT

A centrifugal fan includes a fan rotating about a central axis; and a fan casing enclosing the fan and having an air intake port formed in an axial direction in which the central axis extends and an air exhaust port formed in an orthogonal direction orthogonal to the central axis, radiating fins being provided in the air exhaust port, a tongue portion close to the fan and an inner flow channel going around the fan from the tongue portion to the air exhaust port are formed in the fan casing, and the fan casing has a cover (metallic plate) forming at least one of a top face and a bottom face facing each other in the axial direction, and a protruding portion formed on the cover and projecting toward a blow-out side of the inner flow channel opposite the tongue portion.

FIELD OF THE INVENTION

The present invention relates to a centrifugal fan and an electronic device.

BACKGROUND OF THE INVENTION

An electronic device such as a portable Laptop Personal Computer includes a centrifugal fan that radiates heat generated from electronic components in a chassis to the outside (refer to Japanese Unexamined Patent Application Publication No. 2011-227925, for example). Radiating fins are provided in an air exhaust port of this centrifugal fan.

SUMMARY OF THE INVENTION

In a centrifugal fan, since centrifugal force is applied to discharge fluid, which makes a fluid flow at an air exhaust port uneven, the fluid sometimes hits against only a part of the radiating fins.

The present invention has been made in view of the above-described problem, and aims at improving the cooling performance of the centrifugal fan.

In order to solve the above-described problem, a centrifugal fan according to one aspect of the present invention includes a fan rotating about a central axis and a fan casing enclosing the fan and having an air intake port formed in an axial direction in which the central axis extends and an air exhaust port formed in an orthogonal direction orthogonal to the central axis, radiating fins being provided in the air exhaust port, wherein a tongue portion close to the fan and an inner flow channel going around the fan from the tongue portion to the air exhaust port are formed in the fan casing, and the fan casing has a metallic plate forming at least one of a top face and a bottom face facing each other in the axial direction, and a protruding portion formed on the metallic plate and projecting toward a blow-out side of the inner flow channel opposite the tongue portion.

In addition, in the above-described centrifugal fan, the metallic plate may be a copper plate.

In addition, in the above-described centrifugal fan, the protruding portion may be formed by recessing a part of the metallic plate.

In addition, in the above-described centrifugal fan, the protruding portion may assume a triangular shape having a hypotenuse extending in a direction of crossing a main flow direction on the blow-out side of the inner flow channel when viewed from the axial direction.

In addition, in the above-described centrifugal fan, a plurality of the protruding portions may be provided with space in the main flow direction on the blow-out side of the inner flow channel when viewed from the axial direction.

In addition, in the above-described centrifugal fan, the protruding portion may be provided on the air exhaust port side from the central axis in the main flow direction on the blow-out side of the inner flow channel when viewed from the axial direction.

In addition, in the above-described centrifugal fan, the protruding portion may be formed on one of the top face and the bottom face, and a heat pipe connected to the radiating fins may be provided on the other of the top face and the bottom face.

In addition, an electronic device according to one aspect of the present invention includes the centrifugal fan described before.

The above-described aspects of the present invention can improve the cooling performance of the centrifugal fan.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view of an electronic device according to an embodiment of the present invention.

FIG. 2 is a perspective view of a centrifugal fan according to an embodiment of the present invention.

FIG. 3 is a top cross-sectional view of a centrifugal fan according to an embodiment of the present invention.

FIG. 4 is a cross-sectional view along an arrow I-I in FIG. 3.

FIG. 5 is an enlarged perspective view illustrating a modified example of protruding portions according to an embodiment of the present invention.

FIG. 6 is a cross-sectional view illustrating a modified example of protruding portions according to an embodiment of the present invention.

FIG. 7 is a diagram showing a relationship between the number of protruding portions and cooling performance of the centrifugal fan according to an embodiment of the present invention.

DETAILED DESCRIPTION OF THE INVENTION

FIG. 1 is a perspective view of an electronic device 1 according to an embodiment of the present invention.

The electronic device 1 includes a chassis 10 and a lid 20. This electronic device 1 is a clam shell type Laptop Personal Computer (a so-called note-type Personal Computer).

The chassis 10 is formed in a flat box shape. A keyboard 11 and a touch pad 12 are provided on an upper face 10 a of the chassis 10. The keyboard 11 is disposed at a far side of the upper face 10 a and the touch pad 12 is disposed at a near side of the upper face 10 a. In addition, palm rest portions 13 are formed at both right and left sides of the touch pad 12 on the upper face 10 a.

The lid 20 includes a display device 21 on its face facing the upper face 10 a of the chassis 10. The display device 21 is formed of a liquid crystal display or an organic EL display, for example. A lower end of the lid 20 is coupled to a hinge (not shown) provided on a rear side of the chassis 10 so as to rotate around an axis extending in the right/left direction.

When the lid 20 is opened as shown in FIG. 1, the display device 21 faces a front side and the upper face 10 a of the chassis 10 is opened. On the other hand, when the lid 20 is closed, the lid 20 serves as a cover for covering the display device 21 and the upper face 10 a of the chassis 10.

A motherboard 30, a centrifugal fan 31, and a battery (not shown) etc. are provided in the chassis 10. Air exhaust ports 14 and a USB (Universal Serial Bus) receptacle 32 are opened in the left side face 10 b of the chassis 10. A plurality of the air exhaust ports 14 are formed from the far side to the near side of the left side face 10 b.

The motherboard 30 is fixed by screwing to a plurality of bosses (not shown) provided upright on the bottom of the chassis 10 and is disposed with space and in substantially parallel oppositely to the bottom. This motherboard 30 is disposed at the back side of the keyboard 11 and provided over an area approximately half the size of the chassis 10.

The centrifugal fan 31 is disposed in the far left corner of the chassis 10. The centrifugal fan 31 cools the motherboard 30 via a heat pipe 31 a and exhausts air in the chassis 10 to the outside through the air exhaust ports 14. It is to be noted that air intake ports or gaps (not shown) for taking in outside air into the chassis 10 are formed in the upper face 10 a or a bottom face etc. of the chassis 10.

FIG. 2 is a perspective view of a centrifugal fan 31 according to an embodiment of the present invention. FIG. 3 is a top cross-sectional view of a centrifugal fan 31 according to an embodiment of the present invention. FIG. 4 is a cross-sectional view along an arrow I-I in FIG. 3.

As illustrated in FIG. 2, a pressing member 33 is attached to the heat pipe 31 a extending from the centrifugal fan 31. The pressing member 33 presses the heat pipe 31 a against a heat generation component (for example, CPU) of the motherboard 30. The heat pipe 31 a is thermally connected to radiating fins 34 provided in an air exhaust port 50 b of the centrifugal fan 31 and transports the heat of the heat generation component to the radiating fins 34.

The centrifugal fan 31 includes a fan 40 rotating about a central axis O and a fan casing 50 enclosing the fan 40. An air intake port 50 a and the air exhaust port 50 b are formed in the fan casing 50. The air intake port 50 a is opened in an axial direction in which the central axis O of the fan 40 extends, and the air exhaust port 50 b is opened in an orthogonal direction orthogonal to the axial direction. The above-described plurality of radiating fins 34 are disposed in the air exhaust port 50 b.

The fan casing 50 includes a cover 51 enclosing an upper part of the fan 40 and a frame 52 enclosing a lower part of the fan 40. The above-described air intake port 50 a is formed in the cover 51. In addition, a plurality of air intake ports 50 a are also formed in the frame 52 as illustrated in FIG. 3, and air is taken in from upper and lower faces of the fan casing 50.

The fan 40 includes a hub 41 rotating about a central axis O and a plurality of blades 42 provided on an outer periphery of the hub 41. The fan 40 according to the present embodiment includes a ring plate 43 to which ends of the plurality of blades 42 are annularly connected in a circumferential direction around the central axis O. These hub 41, blades 42, and ring plate 43 are integrally formed of resin material. It is to be noted that at least one of the hub 41, the blades 42, and the ring plate 43 may be formed of metallic material.

The hub 41 is formed in a topped cylindrical shape and connected to a motor (not shown) fixed to the frame 52 of the fan casing 50. The plurality of blades 42 are formed in a substantially S-shape when viewed from the axial direction in which the central axis O extends. This shape of the blades 42 makes noise relatively low even at time of high wind pressure. Such a centrifugal fan 31 is also referred to as a silent fan.

As shown in FIG. 3, a tongue portion 54 close (i.e., functionally adjacent) to the fan 40 and an inner flow channel 55 going around the fan 40 from the tongue portion 54 to the air exhaust port 50 b are formed in the fan casing 50. The inner flow channel 55 forms a scroll flow channel in which a clearance between the fan casing 50 and the fan 40 is narrowest at the tongue portion 54, and the clearance between the fan casing 50 and the fan 40 becomes gradually larger as it goes from the tongue portion 54 to a rotational direction (a direction shown by an arrow in FIG. 3) going around the fan 40.

The cover 51 and the frame 52 are connected via connecting pins 53 on a blow-out (exhaust) side of the inner flow channel 55 opposite the tongue portion 54 on which side the clearance between the fan 40 and the fan casing 50 in the inner flow channel 55 becomes larger. It is to be noted that the blow-out side of the inner flow channel 55 refers, when a first straight line L1 connecting the central axis O and the air exhaust port 50 b in the shortest distance among orthogonal directions orthogonal to the central axis O is regarded as a border line, to a side of the inner flow channel 55 opposite the side where the tongue portion 54 is disposed across the first straight line L1 (that is, it refers to a side of the page lower than the first straight line L1 in FIG. 3).

Protruding portions 60 are protrusively provided on the blow-out side of the inner flow channel 55. The protruding portions 60 are provided on the cover 51, of the cover 51 forming a top face 50 d (refer to FIG. 4) of the fan casing 50 and the frame 52 forming a bottom face 50 e of the fan casing 50. In the present embodiment, the cover 51 is formed of a copper plate (metallic plate). In addition, the frame 52 is formed of a stainless steel plate (metallic plate).

As shown in FIG. 3, a plurality of (two in the present embodiment) protruding portions 60 are provided with space in a main flow direction F on the blow-out side of the inner flow channel 55 when viewed from the axial direction. It is to be noted that the main flow direction F is a direction in which fluid flows straight toward the air exhaust port 50 b along an inner side face 50 c of the fan casing 50 on the blow-out side of the inner flow channel 55 and, in the present embodiment, is a direction parallel to the above-described first straight line L1.

In addition, the protruding portion 60 assumes a triangular shape having a hypotenuse 61 extending in a direction of crossing the main flow direction F when viewed from the axial direction. The hypotenuse 61 makes an acute angle (for example, about 30° to 60°) with the main flow direction F. The radiating fins 34 are disposed on an extension of the hypotenuse 61. The slope of the hypotenuse 61 may be such that the extension of the hypotenuse 61 heads toward the radiating fins 34 disposed in the center of the air exhaust port 50 b.

In addition, the protruding portions 60 are provided on the air exhaust port 50 b side from the central axis O in the main flow direction F when viewed from the axial direction. That is, the protruding portions 60 are provided on a side of the inner flow channel 55 where the air exhaust port 50 b is disposed, when a second straight line L2 orthogonal to the above-described first straight line L1 among orthogonal directions orthogonal to the central axis O is regarded as a border line (that is, they are provided on the left side of the page from the second straight line L2 in FIG. 3). It is to be noted that the protruding portions 60 are more preferably provided on the air exhaust port 50 b side from one third of a radius R of the fan 40, on the air exhaust port 50 b side of the inner flow channel 55.

Such protruding portions 60 are formed by recessing a part of the cover 51 (copper plate) as shown in FIG. 2 and FIG. 4. That is, the protruding portions 60 are formed into a bottomed cylindrical shape with a part of the cover 51 recessed by press working. These protruding portions 60 are formed at positions spaced from the inner side face 50 c of the inner flow channel 55 as shown in FIG. 3. It is to be noted that the protruding portions 60 may be formed by cutting and bending an edge of the cover 51 into a triangular shape as shown in a perspective view of a modified example shown in FIG. 5, and a cross-sectional view of a modified example shown in FIG. 6.

As shown in FIG. 3, the centrifugal fan 31 structured above includes the fan 40 rotating about the central axis O and the fan casing 50 enclosing the fan 40 and having the air intake port 50 a formed in the axial direction in which the central axis O extends and the air exhaust port 50 b formed in the orthogonal direction orthogonal to the central axis O, the radiating fins 34 being provided in the air exhaust port 50 b, the tongue portion 54 close to the fan 40 and the inner flow channel 55 going around the fan 40 from the tongue portion 54 to the air exhaust port 50 b are formed in the fan casing 50, the fan casing 50 has the cover 51 (metallic plate) forming the top face 50 d facing in the axial direction, and the protruding portions 60 projecting toward the blow-out side of the inner flow channel 55 opposite the tongue portion 54 are formed on the cover 51, which distributes the fluid flow in the main flow direction F toward the air exhaust port 50 b along the inner side face 50 c of the fan casing 50 and allows the fluid to hit against the wide radiating fins 34 provided in the air exhaust port 50 b. This can improve the cooling performance of the centrifugal fan 31.

In addition, since the cover 51 on which the protruding portions 60 are formed, is a copper plate in the present embodiment, it has excellent thermal conductivity and good workability. Thus, the protruding portion 60 can be easily formed by recessing a part of the cover 51 by press working etc. It is to be noted that no fluid leaks out from the inner flow channel 55 since forming the protruding portion 60 by recessing does not form any gap or hole in the cover 51 in working compared to the protruding portion 60 of the modified example (cutting and bending) shown in FIG. 5. Thus, it is possible to prevent reduction in air flow of the centrifugal fan 31. In addition, when the heat pipe 31 a is connected to the frame 52 as shown in FIG. 2, the protruding portions 60 can be easily formed while avoiding interference with the heat pipe 31 a by forming the protruding portions 60 on the cover 51.

In addition, in the present embodiment, since the protruding portion 60 assumes a triangular shape having the hypotenuse 61 extending in a direction of crossing the main flow direction F on the blow-out side of the inner flow channel 55 when viewed from the axial direction as shown in FIG. 3, the fluid flow in the main flow direction F can be smoothly distributed toward the radiating fins 34 provided in the center of the air exhaust port 50 b. In addition, since the protruding portions 60 are formed at positions spaced from the inner side face 50 c of the inner flow channel 55, the original fluid flow in the main flow direction F cannot be blocked.

FIG. 7 is a diagram showing a relationship between the number of protruding portions 60 and cooling performance of the centrifugal fan 31 according to an embodiment of the present invention. In the drawing, it is shown that the performance becomes higher in order of “Fair,” “Good,” and “Excellent.” It is to be noted that “ONE PROTRUDING PORTION” indicates the case where the protruding portion 60 is provided only at a position indicated by a symbol (B) in FIG. 3, “TWO PROTRUDING PORTIONS” indicates the case where the protruding portions 60 are provided at positions indicated by a symbol (A) and the symbol (B) in FIG. 3, and “THREE PROTRUDING PORTIONS” indicates the case where the protruding portions 60 are provided at positions indicated by the symbol (A), the symbol (B), and a symbol (C) in FIG. 3.

Two (performance “Excellent”) or three (performance “Good”) protruding portions 60 are more preferable in performance than one protruding portion 60 (performance “Fair”) as shown in FIG. 7. That is, it is found that provision of two or three protruding portions 60 allows the fluid flow in the main flow direction F to be fully distributed. Thus, it is preferable, as shown in FIG. 3, that the plurality of protruding portions 60 are provided with space in the main flow direction F on the blow-out side of the inner flow channel 55 when viewed from the axial direction.

In addition, two protruding portions 60 (performance “Excellent”) are more preferable in performance than three protruding portions 60 (performance “Good”). This is thought to be because the protruding portion 60 at the position indicated by the symbol (C) in FIG. 3 is located at substantially the same position as the central axis O in the main flow direction F. That is, it is thought that the fluid is still in a swirling state in the inner flow channel 55 at the position indicated by the symbol (C), and after the fluid came into collision with the hypotenuse 61 of the protruding portion 60 at an angle, the flow rate of the fluid dropped and the distribution function by the hypotenuse 61 was reduced. Thus, it is preferable, as shown in FIG. 3, that the protruding portions 60 are provided on the air exhaust port 50 b side from the central axis O in the main flow direction F on the blow-out side of the inner flow channel 55 when viewed from the axial direction. More preferably, it is more preferable that the protruding portions 60 are provided on the air exhaust port 50 b side from one third of the radius R of the fan 40 on which side the fluid flows straight along the inner side face 50 c of the inner flow channel 55, on the air exhaust port 50 b side from the central axis O.

Although the embodiments of this invention have been described in detail with reference to the drawings, specific structures are not limited to the above-described embodiments and design etc. without departing from the scope of this invention is also included. Each structure described in the above-described embodiments can be optionally combined unless they are inconsistent with each other.

Although the embodiment of forming the protruding portions 60 on the cover 51 forming the top face 50 d is illustrated by an example in the above-described embodiments, for example, the protruding portions 60 may be formed on the frame 52 forming the bottom face 50 e. In addition, the protruding portions 60 may be formed on both the cover 51 and the frame 52.

Furthermore, when the fan casing 50 intakes the fluid from its top and bottom parts as the present embodiment, the protruding portions 60 may be provided on a part whose fluid intake amount is smaller (that is, the part opposed to a part whose fluid intake amount is larger (the cover 51 or the frame 52)).

Moreover, although the above-described embodiments have been described using a Laptop Personal Computer as one example of an electronic device, for example, the present invention is not limited thereto but may be applied to other electronic devices such as a tablet. 

1. A centrifugal fan, comprising: a fan rotatable about a central axis; and a fan casing enclosing the fan and having an air intake port in an axial direction in which the central axis extends and an air exhaust port in an orthogonal direction orthogonal to the central axis, and radiating fins in the air exhaust port, wherein a tongue portion functionally adjacent to the fan, and an inner flow channel going around the fan from the tongue portion to the air exhaust port, are in the fan casing, and the fan casing has: a metallic plate having at least one of a top face and a bottom face facing each other in the axial direction; and a protruding portion on the metallic plate and projecting toward a blow-out side of the inner flow channel opposite the tongue portion.
 2. The centrifugal fan according to claim 1, wherein the metallic plate is a copper plate.
 3. The centrifugal fan according to claim 1, wherein the protruding portion is formed by recessing a part of the metallic plate.
 4. The centrifugal fan according to claim 1, wherein the protruding portion has a triangular shape having a hypotenuse extending in a direction of crossing a main flow direction on the blow-out side of the inner flow channel when viewed from the axial direction.
 5. The centrifugal fan according to claim 1, wherein a plurality of the protruding portions are spaced apart in the main flow direction on the blow-out side of the inner flow channel when viewed from the axial direction.
 6. The centrifugal fan according to claim 1, wherein the protruding portion is on the air exhaust port side from the central axis in the main flow direction on the blow-out side of the inner flow channel when viewed from the axial direction.
 7. The centrifugal fan according to claim 1, wherein the protruding portion is on one of the top face and the bottom face, and a heat pipe connected to the radiating fins is on the other of the top face and the bottom face.
 8. An electronic device comprising: a centrifugal fan including: a fan rotatable about a central axis; and a fan casing enclosing the fan and having an air intake port in an axial direction in which the central axis extends and an air exhaust port in an orthogonal direction orthogonal to the central axis, and radiating fins in the air exhaust port, wherein a tongue portion functionally adjacent to the fan, and an inner flow channel going around the fan from the tongue portion to the air exhaust port, are in the fan casing, and the fan casing has: a metallic plate having at least one of a top face and a bottom face facing each other in the axial direction; and a protruding portion on the metallic plate and projecting toward a blow-out side of the inner flow channel opposite the tongue portion. 